Primer



J. P. CATLIN Aug. 3, 1954 PRIMER Filed June l2, 1945 llllll-f/ Fing@ MS.Wsw/swf,

INVENTOR LIDHN. F' ILATLIN Patented ug. 3, 1954V PRIMER John P. Catlin,Fairfield, Conn.,'assignor to Remington Arms Company, Inc., Bridgeport,Conn., a corporation of Delaware Application June 12, 1945, lSerial No.599,081

4 Claims.

The present invention relates to a primer, and has for its object toprovide a primer which will be effectually leakV proof in cooperationwith a cartridge case formed Yof aluminum, or of other material havingsubstantially Vthe same characteristics of aluminum.

In the usual cartridge case of brass or steel primer leaks are. by nomeans uncommon, but have been considered only a minor defect becausethey cause no serious trouble. In contrast, however, primer leaks areextremely serious in an aluminum case since the low melting point, highchemical reactivity, and high heat of oxidation of aluminum combine withwhat would otherwise be a trivial primer leak to give very seriouserosion of the primer pocket and the base of the case, the powder gasfrom the fired cartridge causing an inconsequential primer leak todevelop into a melting white-hot erosion of the case, Often the erosionis so serious that a considerable portion of the base material of thecase is burned out in a Very hot flame which seriously erodes the boltface and endanger-s the gunner. In addition to the erosioncharacteristics of aluminum there also exists the mechanical conditionresulting from the combination use of different metals, i. e. a primercup of brass or similar material and a case of aluminum or similarmaterial. The following are examples: elastic expansion of the primercavity diameter of alu- 4 minum case faster than the expansion of abrass primer cup; plastic expansion of the primer cavity diameter undercompressive stresses; lower yield strength of aluminum in comparisonwith other metals, such as brass and steel; and more rapid expansionunder impact loading because of the mass-inertia eiiect, i. e. the morerapid acceleration of a given volume of less dense aluminum incomparison to such metals as brass or steel.

It is an object of the invention to provide a primer wherein acontinuous annular region of contact between the primer cup and primercavity Walls will be maintained under a higher pressure than that of thepowder gas itself, and to accomplish this within sufficiently widelimits so as to maintain an effective seal under any mechanicaldifferential that may exist in the diverse materials of which the primercup and case are constructed.

It is particularly proposed to provide a primer f in which is assembleda conical washer engaged at its periphery with the wall of the primercup, and adapted through the force of the primer explosion to flattenand thrust outwardly at its periphery to produce, by plastic deformationof the primer cup wall and indentation of the primer pocket, acontinuous annular region of contact which firmly and positively sealsthe primer and powder explosion gases within the case.

It has been found that external staking of the case to retain the primercup in the primer pocket has a tendency to give the primer pocket abarrel shape which predisposes toward leaks, and is an object of theinvention to provide a primer which is internally staked at the base ofthe primer pocket through the process of assembling the primer cup inthe pocket, with the result that the staked area not only efectuallyretains the cup against outward thrust under the force of the explosiongases but constitutes a supplementary gas sealing band.

With the above and other objects in View, an embodiment of the inventionis shown in the accompanying drawings, and this embodiment will behereinafter more fully described with reference thereto, and theinvention will be finally pointed out in the claims.

In the drawings:

Fig. 1 is a vertical sectional view of the primer, according to theinvention, showing the primer mixture, anvil, and conical washerassembled therein prior to turning of the lip of the cup,

Fig. 2 is a similar View, showing the lip 0f the cup turned preparatoryto assembly in the primer pocket of the cartridge case.

Fig. 3 is a vertical sectional view, showing the primer assembled withthe cartridge case.

Fig. 4 is a similar view, showing the relation of the parts of theprimer following firing of the primer mixture.

Similar reference characters indicate corresponding parts throughout theseveral iigures of the drawing. f

Referring to the drawings, the primer, according to the illustratedexemplary embodiment of the invention, is adapted to be assembled in theprimer pocket Ill of the cartridge case I I, the latter being formed ofaluminum or material of similar characteristics. The primer comprises a`primer cup I2, preferably formed of brass or ma-- terial of similarcharacteristics, and includes an end wall and a side wall, the end wallin its initial state before assembly of the other parts of the primerbeing preferably domed and the side wall being cylindrical between theend wall and the open end of the cup, as shown in Fig. 1. `With in theprimer cup there is inserted the primer mixture I3, an anvil I4, and aconical washer I5, the anvil being of generally hollow conical form andprovided with oppositely disposed flash openings I6 in its periphery.The Washer l5 is coned at a relatively low angle and snugly engages atits periphery within the wall of the cup I2. The parts of the primer areretained in assembled relation by turning the lower end of the side wallof the cup into downwardly and inwardly inclined conical form below theconical washer I5, as at l1, the domed end wall of the cup beingflattened to cause the central area of the primer mixture to beconstricted, while the marginal area is spread downwardly about theupper end of the anvil. The anvil is preferably formed of brass, whilethe conical washer l is preferably. formed of copper plated suitablyheat treated steel, so that it is relatively hard and strong and has thecapability upon being flattened of exerting outward thrust at itsperiphery upon the wall of the cup to accomplish the plastic deformationof the latter.

The primer is assembled in the primer pocket of the case, as shown inFig. 3, the downward assembling force exerted thereon causing theconical lip I1 to flatten against the base of the pocket, so that itsinner periphery I8 is in substantial register with the flash hole I9 inthe web 20 of the case. At the same time, the area at the base of thecylindrical wall of the cup, in line with the outward thrust upon thelip as the latter is flattened, is forced outwardly into the cylindricalwall of the primer pocket, forming a continuous annular interlockingseal 2 l, produced by the outward plastic deformation of the metal atthe lower corner of the primer cup pressing into and slightly indentingthe wall of the pocket adjacent its base. Thus an internal stake isproduced which effectually prevents the cup from being thrust outwardlyfrom the force of the primer and powder explosion gases. This stakingalso provides a continuous gas sealing band which supplements the gassealing action of the conical washer, as will presently more fullyappear. It will be observed that the internal stake 2l is below the areaof the cup wall in lateral line with the periphery of the conicalwasher, and inwhich area the sealing action of the washer takes place.In assembling the primer into the primer pocket, the end wall of theprimer cup is preferably dimpled at its center, as at 22, in opposedrelation to the point of the anvil.

Upon firing, the explosive force of the primer mixture, as it passesthrough the flash passages IB to the ash hole I3 flattens the conicalwasher l5, as shown in Fig. 4, causing its periphery to thrust outwardlyagainst the wall of the primer cup, which is thereby plasticallydeformed and pressed into the wall of the primer pocket, causing thelatter to be slightly indented, as at 23. This produces a firm andpositive seal along a continuous annular area of contact between theprimer cup and primer pocket. This action, in cooperation with theretention of the primer cup against outward thrust by the internal stake2 I, and the supplemental gas seal provided by this internal stake,provides an effectual seal against the escape between the primer cup andthe primer pocket of the primer and powder explosion gases.

The form of the invention illustrated in the drawings and describedherein is typical and illustrative only, and it is evident that theinvention is capable of embodiments in other forms, all falling withinthe scope of the appended claims, which are to be broadly construed.

What is claimed is:

1. In a primer for cartridges, a primer cup having an end wall and acircumferential side wall and adapted to have a primer charge connedwithin it, an anvil member engaged within said cup, and a deformableexpansion member engaged beneath said anvil having its periphery engagedinternally with said side wall and adapted through the explosive forceof said primer charge to be deformed whereby its periphery is expandedto exert outward pressure on said side Wall.

2. A primer for cartridges comprising a primer cup having an end walland a circumferential side wall, a primer charge confined within saidcup in contact with said end wal-l, an anvil member engaged within saidcup in opposed relation to said end wall, and an apertured conicalwasher member engaged beneath said anvil having its periphery engagedinternally with said side wall and adapted through the explosive forceof said primer charge to be flattened whereby its periphery is expandedto exert outward pressure on said side wall, said circumferential sidewall being flanged inwardly beneath said washer.

3. A primer for cartridges comprising a primer cup having an end walland a circumferential side wall, a primer charge confined within saidcup in contact with said end wall, an anvil member engaged within saidcup in opposed relation to said end wall, and apertured conical washermember engaged beneath said anvil having its periphery engagedinternally with said side wall and adapted through the explosive forceof said primer charge to be flattened whereby its periphery is expandedto exert outward pressure on `said side wall, said circumferential sidewall being flanged inwardly beneath said washer in downwardly andinwardly inclined relation and v adapted upon insertion of the primer inthe primer.cavity of a cartridge to flatten into engage- Yment with'thebase of said cavity and through saidiiattening to be stressed outwardlyinto tight engagement with the wall of said cavity.

4. In combination, a cartridge case having a primer cavity in its head,and a primer engaged in said cavity comprising a primer cup having an`end wall and a circumferential side wall, a primer charge confinedwithin said cup, and a deformable expansion member having its peripheryengaged internally with said side wall, and adapted through theexplosive force of said primer charge to be deformed whereby itsperiphery is expanded to exert outward pressure on said side wall ofsaid cup against the side wall of said cavity, said side wall of saidcup being flanged inwardly beneath said expansion member and beingengaged with the base of said primer cavity, the outer periphery of saidiiange being outwardly projected into interlocking staked engagementwith the side wall of said primer cavity.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 208,589 Gardner Oct. 1, 1878 2,117,885 Hasek May 17, 19382,325,742 Clark Aug. 3, 1943 FOREIGN PATENTS Number Country Date 6,909Great Britain May 22, 1886

